Properties of Highly Porous Hydroxyapatite Obtained by the Gelcasting of Foams

Sepúlveda, Pilar; Ortega, Fernando dos Santos; Innocentini, M. D. M.; Pandolfelli, V. C.

doi:10.1111/j.1151-2916.2000.tb01677.x

Cited by 213 publications

(131 citation statements)

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“…Porous glass foams were produced by adapting the gel-cast foaming process, Figure 1 shows the steps in the process and Table 1 details the reagents and their role in the procedure, based on the work by Sepulveda et al (14)(15)(16)(17)20).…”

Section: Verification Of the Gel-casting Foaming Process Variablesmentioning

confidence: 99%

Melt-derived bioactive glass scaffolds produced by a gel-cast foaming technique

et al. 2011

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Porous melt-derived bioactive glass scaffolds with interconnected pore networks suitable for bone regeneration were produced without the glass crystallising. ICIE 16 (49.46% SiO 2 , 36.27% CaO, 6.6% Na 2 O, 1.07% P 2 O 5 and 6.6% K 2 O, in mol%) was used as it is a composition designed not to crystallise during sintering. Glass powder was made into porous scaffolds by using the gel-cast foaming technique. All variables in the process were investigated systematically to devise an optimal process. Interconnect size was quantified using mercury porosimetry and X-ray microtomography (CT). The reagents, their relative quantities and thermal processing protocols were all critical to obtain a successful scaffold.Particularly important were particle size (a modal size of 8 m was optimal); water and catalyst content; initiator vitality and content; as well as the thermal processing protocol.Once an optimal process was chosen, the scaffolds were tested in simulated body fluid (SBF) solution. Amorphous calcium phosphate formed in 8 h and crystallised hydroxycarbonate apatite (HCA) formed in 3 days. The compressive strength was measured to be approximately 2 MPa for a mean interconnect size of 140 m between the pores with a mean diameter of 379 m, which is thought to be suitable porous network for vascularised bone regeneration.This material has the potential to bond to bone more rapidly and stimulate more bone growth than current porous artificial bone grafts.

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Section: Verification Of the Gel-casting Foaming Process Variablesmentioning

confidence: 99%

Melt-derived bioactive glass scaffolds produced by a gel-cast foaming technique

et al. 2011

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“…As porosity increase and pores are more interconnected and walls get thinner, the crushing strength drops. Their mechanical behaviour in bending seems to follow the trend of other macro-porous alumina materials in literature [38,46] (Figure 13) and also the theoretical predictions using Gibson and Ashby model. All the specimens show a brittle fracture after linear elastic behaviour (Figure 13a), with bending strength decreasing when porosity increases.…”

Section: Characterisationmentioning

confidence: 70%

Complex ceramic architectures by directed assembly of ‘responsive’ particles

Garcı́a-Tuñón¹,

Machado²,

Schneider³

et al. 2017

Journal of the European Ceramic Society

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Surface functionalization of alumina powders with a responsive surfactant (BCS) leads to particles that react to a chemical switch. These 'responsive' building blocks are capable of assembling into macroscopic and complex ceramic structures. The aggregation follows a bottom up approach and can be easily controlled. The directed assembly of concentrated suspensions leads to highly dense (~99%) ceramic components with average 4-point bending strength of ~200 MPa. On the other hand, the emulsification of suspensions with concentrations from 7 to 43 vol% and 50 vol% decane results in emulsions with different properties (stability, droplet size and distribution). The oil droplets provide a soft template confining the alumina particles in the continuous phase and at the oil/water interfaces. Aggregation of these emulsions followed by drying and sintering leads to macroporous (pore sizes ranging from 30 to 4 µm) alumina structures with complex shapes and a wide range of microstructures, from closed cell structures to highly interconnected foams with total porosities up to 83%. Alumina scaffolds with ~55 % porosity can reach crushing strength values above 300 MPa in compression and ~50 MPa in 4-point bending.

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“…Since calcium orthophosphates are either thermally unstable (MCPM, MCPA, DCPA, DCPD, OCP, ACP, CDHA) or have a melting point at temperatures exceeding ~ 1400 °C with a partial decomposition (α-TCP, β-TCP, HA, FA, TTCP), only the first and the second consolidation approaches are used to prepare bulk bioceramics and scaffolds. The methods include uniaxial compaction [198,199], isostatic pressing (cold or hot) [200][201][202][203][204][205][206], granulation [207,208], loose packing [209], slip casting [210][211][212][213], gel casting [188,189,[214][215][216][217][218][219], pressure mold forming [220], injection molding [221], polymer replication [222][223][224][225], extrusion [226][227][228], slurry dipping and spraying [229], as well as to form ceramic sheets from slurries tape casting [124,216,230,231] doctor blade [232] and colander methods might be employed [194][195][196][197]…”

Section: Forming and Shapingmentioning

confidence: 99%

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In the late 1960's, a strong interest was raised in biomedical applications of ceramic materials (named bioceramics a little bit later). Bioceramics was initially used as reasonable alternatives to metals in order to increase their biocompatibility. However, within a short period, it has grown into a diverse class of biomaterials, presently including three essential types: relatively bioinert, bioactive (or surface reactive) and bioresorbable bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30 -40 years. The research was shifted from an initial study on the develop-ment of bioinert bioceramics towards bioactive and bioresorbable bioceramics, and these different types of calcium orthophosphate bioceramics can be tuned through the structural and compositional control. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics has been developed to promote a regeneration of bones. Current biomedical applications of calcium orthophosphate bioceramics include artificial replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmenttation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Potential future applications of calcium orthophosphate bioceramics are demonstrated in drug delivery systems, effective carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

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Properties of Highly Porous Hydroxyapatite Obtained by the Gelcasting of Foams

Cited by 213 publications

References 10 publications

Melt-derived bioactive glass scaffolds produced by a gel-cast foaming technique

Melt-derived bioactive glass scaffolds produced by a gel-cast foaming technique

Complex ceramic architectures by directed assembly of ‘responsive’ particles

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